This proposal is designed to study the mechanism of the cellular regulation of mRNA transcription, processing and cytoplasmic utilization in tissue culture cells and developing embryos of Drosophila melanogaster. The initial approach to these problems will consist of an investigation of the role of non-histone poly (A) minus mRNA and its relationship to poly(A) plus mRNA. My specific objectives are to: (a) Determine the number and kinds of proteins made by the poly(A) minus mRNA from tissue culture cells. This message will be translated in a cell free system and the products analyzed on gels and in reconstitution experiments with appropriate cell fractions. (b) Analyze the kinds of DNA sequences which code for poly(A) minus mRNA. (c) Determine the number of sequences and their abundances in the poly(A) minus mRNA population. A complementary copy of the poly(A) minus molecules will be synthesized with RNA dependent DNA polymerase after affixing a string of nucleotides to the 3' end. The labeled complementary DNA will be hybridized with the RNA. (d) Investigate the role of cytoplasmic adenylation in mRNA utilization during the development of Drosophila embryos.